Cellular body of asphalt and method of producing the same



J. H. YOUNG CELLULAR BODY OF ASPHALT AND METHOD OF PRODUCING THE SAME Filed Nov 8 1926 2 Sheets-Sheet 1 liwenivn:

.a. H. YOUNG CELLULAR BODY' OF ASPHALT AND METHOD OF PRODUCING THE SAME Filed Nov. 8, 1926 2 Sheets-Sheet 2 Patented May 24, I 1927 UNITED STATES PATIENT OFFICE.

JAMES nowAnD YOUNG, or rrrrsmmon, rnu sYLvANIA, AssIoNon 'ro H. a. B0B- nnrsoN courA Y, or rrr'rsnunon, PENNSYLVANIA, A conPonArIoN or rnNN- SYLVANIA.

cnLLULAn 30m! or'AsrnALr AND rm'rnon or PRODUCING THE SAME.

Application filed November 8, 1926. Serial No. 147,112.

This invention relates to a cellular body of asphalt, bitumen and like mater1al,.an 'd has for its object to produce a bod of this character in which the cells or bu bles are uniformly distributed throughout the mass or bod and are of substantially uniform size. he invention further has for'its ob- 'ect to produce the improved cellular body y a novel process as will be described.

To this end a solid or non-cellular body of asphalt or like material, which ma be n mass form or in the shape of the article it is desired to use, is placed in an autoclave or air-tight container into which isfed under pressure a gas which is soluble in asphalt, which gas permeates throughout the body or mass of asphalt, and when said body of asphalt has been subjected to the, external gas pressure asuflicient length of time to be saturated with the gas, the external gas pressure is suddenly reduced or released. This action permits the gas within the body to come out of solution and form bubbles or cells of substantially uniform size which are uniformly distributed throughout the mass.

The mass orbody of saturated asphalt may be heated to a tem erature sufficient to renderit plastic, just efore the pressure of the s is released, which permits the gas bubb es to expand, once they are formed, but

care is taken tokeep the asphalt at a temperature low enough to prevent m1grat1on 'of the as bubbles, and practically confine thel'nsuhstantially at theiplace in the mass at which they are formed, with the result that the bubbles or cells are of substantially uniform size and are uniformly distributed throughout the mass. The solution of the,

gasin the asphalt may and'preferably will be facilitated by agitating the mass by stirring the'same while heated to'a temperature above its melting ipoint, and then reducing the temperature 0 the asphalt to below its melting point before the gas pressure is reduced to cause the formation of the gas bubbles and to prevent their migration in the mass. One-form ofapparatus is hereinshown with which'the improved cellular asphalti'c body may be I commercially produced;

These "and other features of the invention will be pointed out in the claims at the end of this specification.

Fig. 1 conventionally represents in section .F on an enlarged scale a portion of a body.

or'mass of asphalt or like material embodym the invention; 1g. 2 conventionally represents the noncellular body or mass before treatment, and

Fig. 3 conventionally representsone form of apparatus in which theconversion maybe efi'ected.

Referring to the drawing, 10 represents a body or mass of material to be treated, which material may consist of asphalt alone or mixtures of asphaltities, or mixtures of natural and artificial asphalt, or mixtures of tars, stearine pitches, waxes and vegetable oils, coal tar, vegetable tar pitches, bitumens a'nd l1ke materials, and said materials will be hereinafter referred to as asphalt. The body of asphalt 10, as shown in Fig, 2, is represented as solid and free from cells, and is relatively heavy.

The present invention has for its object to convert the relatively heavy and non-cellular body or mass 10 of asphalt into a relatively light cellular body 12, represented in Fig. 1, Whose specific gravity is substantially lower than that of the body 10, and in which the cells 13 are of substantially the same size and uniformly distributed throughout the body 12. The cells 13 are formed by bubbles of gas, and to obtain gas bubbles of substantially the same size and have them uniformly distributed throughout the asphalt body, the

non-cellular body 10 is subjected to the action of a gas which is soluble in asphalt, which gas is under throughout the mass. After the asphalt. body 10 has been subjected tothe gas pressure a sufficient length of time to ensure s'olu bility in the body 10 of asphalt, the gas pressure is suddenly released or reduced, and,'since the solubility of the gasin asphalt .varies'directly with the pressure, a .stateof super saturation exists. when the pressure is suddenly released, which causes the gas to come out of solution in the form of bubbles, represented'by 13 in Fig. 1, andthese gas bubbles are of substantially the same size .and are uniformly distributed throughout (the body of asphalt, thereby converting the non-cellular asphalt body lOinto a cellular body 12, whose cells 13 are substantially of the same'size, and are uniformly distributed throughout the body, as represented in It may be preferred to subject the non pressure and permeates cellular body 10 to a temperature sufficiently high to render it more or less plastic while under the external gas pressure, so that when the gas pressure is suddenly released or reduced, the asphalt body 10 may be ust plastic enough to permit the gas bubbles, after being formed, to expand slightly, but said asphalt body is kept at a temperature low enough to prevent free or migratory movement of the gas bubbles toward the outer surface of the body.

To aid rapid saturation of the asphalt body with gas soluble in asphalt, the asphalt body may be subjected to a temperature sufficiently high to render the asphalt body fluid and thus allow it to be agitated by stirrin or by bubbling with the gas while said asp ialt body is subjected to the external gas pressure, and then reducing the temperature of the asphalt body suiiicientl low to bring it into the plastic condition a ove described before the external gas pressure is released. It will be observed that when the external gas pressure is released, the asphalt body is in a condition which allows the gas within the asphalt to come out of solution and form bubbles which expand slightly and form cells within the asphalt body, but

which condition is such as to localize the gas bubbles, confining them to the place at which they are formed and preventing them from migrating or passing freely through the body of as halt. As a result, a superior cellular aspha t body is produced in which the cells or bubbles are of substantially the same size and uniformly distributed throughout the mass or body.

The improved cellular asphalt body mayl be produced in any suitable apparatus, suc as an autoclave or vessel having provision for rendering it gas-tight, and for supplying it with gas which is soluble in asphalt, for releasing the gas-pressure, for raising the temperature of the asphalt body before re leasing the pressure, for agitating the mam at the increased temperature, and if desired for automatically removing the cellular asphalt from the autoclave. An apparatus of gases soluble in this character is conventionally represented in Fig. 3, wherein 20 represents the air-tight vessel or autoclave; 21, the gas supply p1pe rovided with a valve 22; 23, the outlet pipe or the vessel 20; 24, a heater for the autoclave 20 in the form of a steam jacket having a steam inlet pipe 25 and a steam outlet 26; 27, a closure or valve for the outlet pipe 23; and 28, a suitable die connected with the out let pipe and in which the mass is expanded into t e shape desired.

While the gas which I prefer to use is a mixture of gases of the so-called' aliphatic series, such as natural gas, I do not desire to limit the invention in this respect as other asphalt under pressure may be used. r

The improved asphalt body is light and of uniform cellular structure and is capable of being used to advantage in all situations in which asphalt may be used, and particularly as an insulating material.

Prior to this invention I am aware that so-ealled sponge asphalt has been produced, but such product differs materially from the product herein described, in that it is lacking in the uniformity in size of the cells or bubbles, and also in the uniform distribution of said cells or bubbles throughout the mass or body of asphalt, and further in the character of the gas contained in the cells or bubbles, that in the so-called sponge asphalt being air, while that in the product herein dcscribed being a gas other than air.

The non-cellular asphalt body may have incorporated with it other materials such as lamp black, mineral fillers, etc.

The density of the cellular asphalt body and the size of the bubbles or cells may be varied by controlling the pressure of the soluble gas. Ver porous bodies of low specific gravit may e obtained b using a high pressure 0 the soluble gas, and denser products may be obtained by using a lower gas pressure.

While any of the materials above mentioned may be used to make the improved product, it is preferred to use a mixture of stearine pitch and asphalt of commerce. It is preferred to use an asphalt having a melting point from 300 to 400 F. (B. and R. method), and to admit a substantial quantit-y of this asphalt into the vessel 20 through the inlet 30. After the desired quantit of asphalt has been supplied to the vesse 20, the inlet 30 is closed and the vessel rendered gas-tight. The asphalt is then melted by heating the vessel 20 to a temperature above the melting point of the asphalt, which for example may be supposed to be 300 F. This heating may be effected by steam admitted into the jacket 24. Natural gas under a pressure of 200 lbs. per square inch isthen admitted into the vessel 20 through the pipe 21. The gas permeates through the mass of asphalt and saturates the latter, which is facilitated by stirring the asphalt mass with the stirrer 32 which is rotated by power in any suitable manner. The asphalt mass may be subjected to the action of the gas under pressure for a number of hours. Ten hours is deemed suflicient to obtain the results desired. After the asphalt mass has been subjected to the natural gas a suflicient length of time to ensure the complete saturation of the mass with the gas, the temperature of the asphalt mass is reduced from a point above its melting point to a temperature substantially below said melting point, and preferably to a point about 20 lower than said melting point. This is effected by cutting off or reducing the steam supply. At or about the time the temperature of the mass of asphalt has been reduced, the asphalt is suddenly subjected externally to a reduced gas pressure, which is efiected in the present instance by opening the Valve 27 in the outlet pipe 23 and allowing the saturated asphalt to be forced into a die 28 which communicates with the atmosphere and is of the desired size and shape to permit the ,saturated asphalt to be expanded into the cellular construction of body represented in Fig. 1, and to impart to the latter the shape it is desired the finished product should have.

If desired, the asphalt body in the form or shape of the finished article, may be treated in the same manner, except that the melting and stirring and the extrusion of the asphalt is omitted.

What I claim is: r

1. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in subjecting the non-cellular body to external pressure of a gas soluble in asphalt, and then reducing the external pressure upon the as halt to permit the gas within the asphalt ody to form bubbles therein.

2. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in subjecting the non-cellular body to external pressure of a gas soluble'in asphalt, heating the non-cellular body to render. it plastic while under said external gas pressure, and then reducing the external pressure upon the asphalt to permit the gas within the body to form bubbles therein.

3. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in saturating the non-cellular body with gas soluble inv asphalt, causing the gas within the body to;

form bubbles therein, and confining the bub bles Within the body substantially at the places where they are formed.

4. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in heating the asphalt to a temperature above its melting point, agitating theheated asphalt, subjecting theheated and a itated asphalt tothe pressure of a gas solu le in asphalt, reducing the temperature of the heated asphalt below its melting point While under the gaseous pressure, and reducing the external pressure upon the asphalt after the tem perature of the asphalt has been reduced to below its melting point.

5. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in melting the asphalt, agitating the melted asphalt, subjecting the agitated melted asphalt to the pressure of a gas soluble in as halt, reducing the temperature of the heate asphalt below its melting point while under the gaseous pressure, and reducing the external pressure upon the asphalt after the temperature of the asphalt has been reduced to below its melting point.

6. The method of treating asphalt to convert it from a non-cellular into a cellular condition, which consists in subjecting the non-cellular body to external pressure of a gas soluble in asphalt, and simultaneously expanding and shaping the treated asphalt to form a cellular body of the desired shape.

7. A cellular body of asphalt having its cells containing a gas soluble in asphalt under pressure and other than air. 4

8. A cellular body of asphalt havingit cells containing natural gas.

In testimony whereof, I have signed my name to this specification.

JAMES HOWARD YOUNG. 

